I was browsing Dogfunk and began comparing specs for identical boards at different lengths. I compared the effective edge, waist width, and sidecut radius. I took a look at the NS Evo and according to their site the specs are as follows:

Evo 152
EE: 1220mm
WW: 244mm
SR: 7.2m

Evo 154
EE: 1220mm
WW: 251mm
SR: 7.22m

My question is, if the same rider at 5'8 1/2" 160lbs-165lbs rode both boards, what would be the difference in performance between the 2 lengths? What could he expect to lose or gain with each size?

Yeah, on hardpack you still want the longest effective edge you can reasonably handle, and a longer sidecut radius will mean you've got to lean the board more to get the same turn. There's a reason the race boards are super long and have super long sidecut radii!

Again, I still think they're a little short for your weight. The 154 will probably be fine, but longer wouldn't hurt if you want to carve on hardpack.

Yeah, on hardpack you still want the longest effective edge you can reasonably handle, and a longer sidecut radius will mean you've got to lean the board more to get the same turn. There's a reason the race boards are super long and have super long sidecut radii!

Again, I still think they're a little short for your weight. The 154 will probably be fine, but longer wouldn't hurt if you want to carve on hardpack.

Yeah, Leo advised the 154 as well. I was just curious because, as you also pointed out, there is not a big difference the two. See what happens when your season ends early...in the house with cabinet fever over analyzing shit!